Interpreting the IgG & IgM Western Blot For Lyme Disease
©2004 Melissa Kaplan
WORK IN PROGRESS!!!
The IgG and IgM Western Blot provides results in a way that lets us visualize the patient's antibodies. It is more sensitive and specific than the ELISA and EIA (that is, it is more likely to show positives where the ELISA/EIA showed negatives). The IgG and IgM WB should always be used when the Lyme IgG/IgM antibody serology has returned an equivocal or positive result.
If the patient is highly symptomatic of Lyme, there is actually no point in doing the ELISA or EIA serum tests, as they do not have the sensitivity or specificity of the Western Blot that is needed to have a prayer of detecting Borrelia burgdorferi (Bb), the organism that causes Lyme disease.
Contrary to what many insurance companies believe, the IgG and IgM Western Blot for Lyme disease are not the same test. Some companies will deny one and pay the other, claiming they are the same test or duplicative of one another. IgG and IgM are two completely different antibodies.
IgM antibodies are the first antibodies to be produced in the body in response to an infection, and is produced in great quantity. IgM antibodies are large, up to six times larger than the IgG antibodies. IgM antibodies, when present in high numbers, represent a new active infection or an existing infection that has become reactivated. Over time, the number of IgM antibodies will decline as the active infection is resolved.
IgG antibodies are produced once an infection has been going on for a while, and may be present after the infection has been resolved. Generally speaking, the presence of IgG antibodies to an organism when accompanied by a negative IgM test for the same organism means that the person was exposed to that organism at one time and developed antibodies to it, but does not have a current active infection of that organism. When it comes to Borrelia burgdorferi (Bb), the organism responsible for Lyme disease, that is not necessarily the case.
To recap, depending on the numbers,
Bb can hide in the brain and cerebral spinal fluid (CSF) and by altering its surface proteins, can remain invisible to the immune system for a long period of time. Once the immune system figures out what it is and starts making antibodies to it, it shifts is surface proteins once again, fooling the body into thinking the infection is over.
Bb can also turn itself into undetectable cysts and various other forms (called L-forms) which also help it elude the immune system. If the immune system can't see it, the immune system can't make and, or only insufficient antibodies, which all contribute towards making the organism impossible to detect by any testing methodology, including WB. Thus, blood and urine tests for Bb can be negative, even if the patient is "challenged" by being given high dose injections of antibiotics to try to trigger a reaction from or partial die-off of Bb that will cause it to show up in the blood or urine.
As can be seen from the table below, The CDC's criteria for what constitutes a positive result is very conservative. As a result, it is believed by those who have been treating Lyme patients for years, and by those developing other, more sensitive tests, that the CDC criteria miss most cases of borreliosis and, as a result of that underreporting, grossly understate the incidence of Lyme in the United States.
Note On IGeneX
Positive (+ or +/-) IgG results on Bands 31 or 34 kDa may occur after vaccination in otherwise uninfected people.
IGeneX considers the IgM equivocal if only one of the @ bands are present.
Art Doherty. And The Bands Played On
IGeneX, Inc. Lyme Disease Western Blot
Coleman JL, Benach JL. Characterization of antigenic determinants of Borrelia burgdorferi shared by other bacteria. J Infect Dis. 1992 Apr;165(4):658-66
Flisiak R, Wierzbicka I, Prokopowicz D. Western blot banding pattern in early Lyme borreliosis among patients from an endemic region of north-eastern Poland. Rocz Akad Med Bialymst. 1998;43:210-20.
Mervine, Phylllis. CALDA. Personal communication. 2004.
Ravyn MD, Goodman JL, Kodner CB, Westad DK, Coleman LA, Engstrom SM, Nelson CM, Johnson RC. Immunodiagnosis of human granulocytic ehrlichiosis by using culture-derived human isolates. J Clin Microbiol. 1998 Jun;36(6):1480-8.
Tylewska-Wierzbanowska S, Chmielewski T. Limitation of serological testing for Lyme borreliosis: evaluation of ELISA and western blot in comparison with PCR and culture methods. Wien Klin Wochenschr. 2002 Jul 31;114(13-14):601-5
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